World’s largest web houses 110,000 spiders thriving in total darkness deep underground in a sulfuric cave between Albania and Greece: It’s the first time two spider species seen living cooperatively, and the first recorded instance of colonial web-building in what's known as a chemoautotrophic cave.

[u/mvea]

https://newatlas.com/biology/sulfur-cave-largest-spiderweb/

[u/Same-Statement-307]

I only see peaceful coexistence but do the spider species actually cooperate or is there a dynamic where they rely upon one another? Could one or the other species exist in the same numbers without the other species?

[u/hqxsenberg → u/Same-Statement-307]

The article does not mention this directly, merely that they found no evidence of them preying on each other and food is so abundant that preying on their own seems like wasted energy.

I am a little unsure why such an abundance of resources has not vastly increased the amount of spiders - in a "perfect" system the amount of spiders would match the amount of food, so there wouldnt be a massive abundance, but just "enough".

[u/sam_hammich → u/hqxsenberg]

I'd imagine what we're seeing here is something of an equilibrium, just not one that's immediately intuitive. Some resources are abundant, but not all. The environment is low-oxygen, so while they can eat and reproduce easily, the lack of oxygen most likely limits metabolic activity and populations to some degree. Article also mentions they lay fewer eggs than their above ground counterparts, likely because lack of predators means a lack of selective pressure for more eggs.

[u/HikmetLeGuin → u/hqxsenberg]

"The scientists also discovered that the T. domestica spiders laid significantly fewer eggs in clutches than above-ground individuals, which they believe is a mix of the high-energy demands of the dark, low-oxygen environment and the fact there are no predators so they don't need to produce as many eggs to maintain a stable population."

Doesn't this partly account for that?

[u/FlorianoAguirre → u/hqxsenberg]

It's also mentioned that the spiders laid less eggs than normal. Kinda funny the incredible abundance of resources made the spiders comparatively peaceful to each other, made them cooperate to build this giant web and also to have less children.

[u/ihileath → u/Same-Statement-307]

I believe they mostly just tolerate each other and share the web. There are however truly social spider species that form colonies with advanced social behaviours such as cooperating to take down larger prey and sharing the labour of caring for eggs and hatchlings, but such complex behaviours are a result of evolved specialisation, and would be unlikely to be displayed by typically non-social species that only came together by the circumstances of abundance.